If you're looking to have a little weekend science-lab fun with lasers it turns out that in the heart of every cheap laser pointer is a fire-starting, balloon-popping, monster.
What's the secret to upgrading your cheap laser from a boring presentation tool to a goggles-on-for-safety experiment? Over at Wired's How-To wiki they detail how to take apart a cheap laser pointer and find the adjustable variable-resistor on the circuit board inside. Tweak that resister with a small jeweler's screw driver and you can crank the juice up on your laser pointer—not too far or you'll burn it out! Visit the wiki at the link below for full instructions.
Inspired by the potential burnination of your cheap laser? Have a warranty-voiding bit of fun to share? Lets' hear about it in the comments. Oh, and please be careful, and proceed at your own risk.
Amp Up a Laser Pointer [Wired How-To Wiki]